This invention was not developed and is not related to any federally sponsored research and development.
The invention relates to a process for the production of a composition enriched in isoflavone values by treatment of a biomass containing the isoflavone values.
Isoflavones are a unique class of plant flavonoids that have a limited distribution in plants and can be described as aromatic ketones. The isoflavones in the plant sources are generally in the glycosolated form.
Recently the health benefits of the isoflavones have been investigated and a favorable portrait of the physiological and health benefits associated with isoflavones has been published in the press and the literature.
Some of the references to physiological health effects include Cheng et al., Estrogenic Activity of Some Naturally Occurring Isoflavones, Annals of the New York Academy of Sciences, Vol. 61; Pages 652-654; Catabolic Activity of Isoflavones U.S. Pat. No. 3,864,362, Feb. 4, 1975; Prevention of Osteoporosis, U.S. Pat. No. 5,424,331, Jun. 13, 1995; Treatment of Diabetic Male Sexual Dysfunction, U.S. Pat. No. 5,523,087, Jun. 4, 1996; Management of Premenstrual Syndrome, U.S. Pat. No. 5,569,459, Oct. 29, 1996; Treatment of Menopausal and Premenstrual Symptoms, U.S. Pat. No. 5,498,631, Mar. 12, 1996; Compounds and Pharmaceutical Compositions for the Treatment of Hypoovarianism, EP 0 129,667, A1 published Jan. 2, 1985; Method for Treatment of Osteoporosis, EP 0 135,172 A2, published Mar. 27, 1985: Fast, June; the Effect of Genistein on the Fertility of Mice, J. Endocrinology, Vol. 13, 94-100, October, 1955; Food for Controlling Cancer, Bone Disease or Immunity Obtained by Fermenting Pulses esp. Soy Beans, Hydrolyzing Protein and Forming Aglycone of Isoflavone Glycoside, U.S. Pat. No. 5,885,632, Mar. 22, 1994; Estrogenic, antioxidant, antihaemolytic, antibacterial, anti-hyperlipidemic, anti-hypercholesterolemic and anti-cancer activity are disclosed in JP 5170756, Sep. 7, 1993.
The isoflavones are generally present in plant substrates in relatively low concentrations. It is desirable to provide isoflavones in a higher concentration so that they can be utilized as a dietary supplement to provide enhanced levels of isoflavones without consumption of substantial amounts of the natural products from which the isoflavones are derived.
A particularly good source of isoflavone values have been materials derived from soybeans, however isoflavones values are also present in substantial amounts in plants such as red clover.
U.S. Pat. No. 5,554,519 discloses a method for preparing genistein by fermentation and recovering the genistein from the fermentation broth by extraction with a water immiscible organic solvent at a pH of from about 8 to about 11. Solvents such as ethyl acetate, amyl acetate, chloroform, ethylene dichloride, ethers, ketones, and alcohols, the preferred solvents include n-butanol, amnyl acetate and ethyl acetate. The genistein is recovered from a dilute aqueous solution of carbohydrates and proteins. Genistein is the only isoflavone present so there is no concern with extracting other isoflavones from the fermentation medium.
U.S. Pat. Nos. 5,320,949, 5,352,384, 5,637,561, and 5,637,562 disclose methods for preparing aglucone isoflavone enriched soy products. The glucone isoflavones are extracted from the soy starting material with an aqueous extractant to extract protein and glucone isoflavones, the extract is treated with a glucosidase to convert gluronc isoflavoaes to aglucone isoflavones and the pH adjusted to precipitate the aglacone isoflavanes which are recovered with the soy material. The process provides a soy product enriched in aglucone isoflavone.
U.S. Pat. No. 5,670,632 discloses a method for recovering isoflavones from a soy extract. The soy extract at a pH of about 9 is treated by a solids separation means to remove suspended solids. The solution less the solids is contacted with a highly polar cationic exchange resin and the isoflavone values are desorbed from the polar resin by an acidic aqueous alkanol containing 1-3 carbon atoms. The isoflavone values are recovered from the solvent.
U.S. Pat. No. 5,679,806 discloses a process for isolation and purification of isoflavones from biomass sources. The biomass is extracted with a solvent to provide a crude extract. The preferred solvent is alcohol. The crude extract is diluted with water and contacted with a reverse phase matrix in a column to adsorb the isoflavone values and the isoflavone values are desorbed and eluted in fractions from the reverse phase matrix. The individual isoflavones recovered from the reverse phase matrix in the absorbent column can be further purified.
U.S. Pat. No. 5,702,752 discloses a process for recovering isoflavone values from a soy molasses feed stream, in particular, the recovery of genistein. An aqueous soy extract is subjected to ultrafiltration to recover isoflavones as a permeate and the isoflavones further purified to recover isoflavones in high concentration.
U.S. Pat. No. 5,821,361 discloses a method for recovering isoflavones from soy molasses. A solution of soy molasses in water is treated at a pH and temperature to convert isoflavone conjugata to isoflavone glucosides, precipitating the isoflavone glucosides and separating the isoflavone glucosides from the solution by mechanical means such a filtration, centrifugation and the like. Recovering the solids comprising isoflavone glucosides.
U.S. Pat. No. 4,428,876 is directed to a process for isolating saponins and flavonoids from leguminous plants. The plant material is extracted with a dilute aqueous alkaline solution, the insoluble material is separated from the extract and the saponins and flavonoids are recovered by adsorption in a slightly polar adsorbent resin and eluted with a polar solvent.
JP 05176756A discloses recovery of isoflavone derivatives from soy based materials by extracting the soy based material with 80% methanol. The extract was filtered and evaporated to produce a solid. The solid was dissolved in ethanol and the isoflavone derivatives recovered by adsorption in an adsorption resin, eluted with 80% ethanol and the material dried to provide a composition containing at least 90% isoflavone derivatives.
JP 61247396A discloses a method from preparing genistein by fermentation, separating the solids from the aqueous phase, extracting the aqueous phase with an organic solvent and recovering the genistein from the solvent by adsorption and elution from an adsorption resin bed.
The process of the present invention comprises extracting isoflavone values from plant material and recovering the isoflavone values from the extracting solvent. The solvent is a composition which has an affinity for the isoflavone values in the plant material. Preferably the solvent has a higher affinity and is selective for the isoflavone values over the other substituents in the plant material. The extraction separates the isoflavone values from a portion of the other materials in the plant material.
The isoflavone values are recovered from the solvent preferably by a method that further purifies the recovered isoflavone values. The isoflavone values can be recovered from the solvent by methods such as evaporation, precipitation, and crystallization and contact or washing with a nonsolvent or antisolvent for the isoflavone values. Fine particles of the isoflavone values, which can be formed in the washing step, are difficult to recover due to the small particle size. The small isoflavone particles can be agglomerated by addition of small amounts of water to a slurry of the isoflavone values in a nonsolvent for the isoflavone values and can then be readily separated from the solvent.
The purity of the isoflavone values recovered from the plant materials is dependent upon the nature of the solvent utilized, and the steps of recovering the isoflavone values from the solvent extract.